Extrinsic Stimulation Research Articles

Mechanical heterogeneity in a soft biomaterial niche controls BMP2 signaling

The extracellular matrix is known to impact cell function during regeneration by modulating growth factor signaling. However, how the mechanical properties and structure of biomaterials can be used to optimize the cellular response to growth factors is widely neglected. Here, we engineered a macroporous biomaterial to study cellular signaling in environments that mimic the mechanical stiffness but also the mechanical heterogeneity of native extracellular matrix. We found that the mechanical interaction of cells with the heterogeneous and non-linear deformation properties of soft matrices (E < 5 kPa) enhances BMP-2 growth factor signaling with high relevance for tissue regeneration. In contrast, this effect is absent in homogeneous hydrogels that are often used to study cell responses to mechanical cues. Live cell imaging and in silico finite element modeling further revealed that a subpopulation of highly active, fast migrating cells is responsible for most of the material deformation, while a second, less active population experiences this deformation as an extrinsic mechanical stimulation. At an overall low cell density, the active cell population dominates the process, suggesting that it plays a particularly important role in early tissue healing scenarios where cells invade tissue defects or implanted biomaterials. Taken together, our findings demonstrate that the mechanical heterogeneity of the natural extracellular matrix environment plays an important role in triggering regeneration by endogenously acting growth factors. This suggests the inclusion of such mechanical complexity as a design parameter in future biomaterials, in addition to established parameters such as mechanical stiffness and stress relaxation.

External magnetic field non-invasively stimulates spinal cord regeneration in rat via a magnetic-responsive aligned fibrin hydrogel

Magnetic stimulation is becoming an attractive approach to promote neuroprotection, neurogenesis, axonal regeneration, and functional recovery in both the central nervous system and peripheral nervous system disorders owing to its painless, non-invasive, and deep penetration characteristics. Here, a magnetic-responsive aligned fibrin hydrogel (MAFG) was developed to import and amplify the extrinsic magnetic field (MF) locally to stimulate spinal cord regeneration in combination with the beneficial topographical and biochemical cues of aligned fibrin hydrogel (AFG). Magnetic nanoparticles (MNPs) were embedded uniformly in AFG during electrospinning to endow it magnetic-responsive feature, with saturation magnetization of 21.79 emu g−1. It is found that the MNPs under the MF could enhance cell proliferation and neurotrophin secretion of PC12 cells in vitro. The MAFG that was implanted into a rat with 2 mm complete transected spinal cord injury (SCI) effectively enhanced neural regeneration and angiogenesis in the lesion area, thus leading to significant recovery of motor function under the MF (MAFG@MF). This study suggests a new multimodal tissue engineering strategy based on multifunctional biomaterials that deliver multimodal regulatory signals with the integration of aligned topography, biochemical cues, and extrinsic MF stimulation for spinal cord regeneration following severe SCI.

The Impact of TRAIL on the Immunological Milieu during the Early Stage of Abdominal Sepsis

Despite intensive scientific efforts, the therapy of peritonitis is presently limited to symptomatic measures, including infectious source control and broad-spectrum antibiotics. Promising therapeutic approaches to reduce morbidity and mortality are still missing. Within the early phase of abdominal sepsis, apoptosis of neutrophil granulocytes is inhibited, which is linked to tissue damage and septic shock. TNF-related apoptosis-inducing ligand (TRAIL) is a promising agent to stimulate neutrophil apoptosis. However, the underlying mechanisms have not been elucidated so far. The objective of the present study was to characterize the molecular mechanisms of TRAIL-stimulated apoptosis in early abdominal sepsis. Therefore, the murine sepsis model Colon ascendens stent peritonitis (CASP) was applied in wild type (WT) and TRAIL knock-out (TRAIL-/-) C57/BL6j mice. Neutrophil granulocytes were isolated from spleen, blood, bone marrow, and peritoneal lavage using magnetic-activated cell sorting. Neutrophil maturation was analyzed by light microscopy, and apoptotic neutrophils were quantified by fluorescence-activated cell sorting (FACS). Western blot and FACS were used to investigate expression changes in apoptotic proteins and TRAIL receptors. The impact of TRAIL-induced apoptosis was studied in vitro. In septic mice (CASP 6 h), the number of neutrophils in the BM was reduced but increased in the blood and peritoneal lavage. This was paralleled by an increased maturation of neutrophils from rod-shaped to segmented neutrophils (right shift). In vitro, extrinsic TRAIL stimulation did not alter the apoptosis level of naïve neutrophils but stimulated apoptosis in neutrophils derived from septic WT and TRAIL-/- mice. Neutrophils of the bone marrow and spleen showed enhanced protein expression of anti-apoptotic Flip, c-IAP1, and McL-1 and reduced expression levels of pro-apoptotic Bax in neutrophils, which might correlate with apoptosis inhibition in these cells. CASP increased the expression of intrinsic TRAIL in neutrophils derived from the bone marrow and spleen. This might be explained by an increased expression of the TRAIL receptors DR5, DcR1, and DcR2 on neutrophils in sepsis. No differences were observed between septic or naïve WT and TRAIL-/- mice. In conclusion, the present study shows that neutrophil granulocytes are sensitive to TRAIL-stimulated apoptosis in the early stage of abdominal sepsis, emphasizing the promising role of TRAIL as a therapeutic agent.

Electrical devices for functional visceral pain.

Several studies have documented correction of dysmotility in several regions of the gastrointestinal tract based on electrical stimulation of extrinsic nerves supplying those regions. In this issue of Neurogastroenterology and Motility, Ma et al. (2023) document the effect of transcutaneous neuromodulation applied by acustimulation at ST36 for ineffective esophageal motility in patients with gastroesophageal reflux disease. In addition to motor effects, there were also significant effects on GERD symptoms, raising the question whether extrinsic electrical nerve stimulation of the gut can reduce symptoms through effects that target sensation. This brief review summarizes evidence regarding the application of electrical acustimulation, transauricular electrical stimulation, and sacral electrical or magnetic stimulation to reduce abdominal or pelvic pain.

Putting practice under the microscope: The perceived uses and limitations of slow instrumental music practice

Practicing slowly is a commonly used, intuitive approach to music learning, and is widely considered the bedrock of musical skill acquisition. Yet, little is known about the different approaches and techniques musicians use when practicing slowly. This study investigated instrumental musicians’ perspectives on the uses, limitations, and specific techniques of slow music practice, through qualitative thematic analysis of responses to an online questionnaire. Generally, slow practice was perceived as a useful, and often necessary, part of learning. Furthermore, we identified four perceived functions of slow practice. They were managing information load; building a foundation for motor learning; creative and critical problem-solving; and regulating emotional, mental, and perceptual states. We propose a possible underlying mechanism of these functions: reduction of extrinsic cognitive load and stimulation of germane cognitive processes. Respondents also perceived potential technical-practical and emotional-cognitive malfunctions of slow practice, as well as possible strategic pitfalls of using slow practice. Specific techniques of slow practice included the use of tempo organization methods and strategies to complement slow practice. This provided insight into how biomechanical differences between slow and fast playing might be bridged. Findings have implications for music education and understanding the psychology of musical skill acquisition.

The Synergistic Effect of Cyclic Tensile Force and Periodontal Ligament Cell-Laden Calcium Silicate/Gelatin Methacrylate Auxetic Hydrogel Scaffolds for Bone Regeneration.

The development of 3D printing technologies has allowed us to fabricate complex novel scaffolds for bone regeneration. In this study, we reported the incorporation of different concentrations of calcium silicate (CS) powder into fish gelatin methacrylate (FGelMa) for the fabrication of CS/FGelMa auxetic bio-scaffolds using 3D printing technology. Our results showed that CS could be successfully incorporated into FGelMa without influencing the original structural components of FGelMa. Furthermore, it conveyed that CS modifications both the mechanical properties and degradation rates of the scaffolds were improved in accordance with the concentrations of CS upon modifications of CS. In addition, the presence of CS enhanced the adhesion and proliferation of human periodontal ligament cells (hPDLs) cultured in the scaffold. Further osteogenic evaluation also confirmed that CS was able to enhance the osteogenic capabilities via activation of downstream intracellular factors such as pFAK/FAK and pERK/ERK. More interestingly, it was noted that the application of extrinsic biomechanical stimulation to the auxetic scaffolds further enhanced the proliferation and differentiation of hPDLs cells and secretion of osteogenic-related markers when compared to CS/FGelMa hydrogels without tensile stimulation. This prompted us to explore the related mechanism behind this interesting phenomenon. Subsequent studies showed that biomechanical stimulation works via YAP, which is a biomechanical cue. Taken together, our results showed that novel auxetic scaffolds could be fabricated by combining different aspects of science and technology, in order to improve the future chances of clinical applications for bone regeneration.

Comparing motivational features between feedback givers and receivers in English speaking class

Abstract In peer feedback literature, the topic of motivation for feedback is not sufficiently explored, and attention to motivational differences between feedback givers and receivers unbalanced. To address this gap, the present study tracked motivational changes of Chinese students performing consecutively the roles of written-feedback givers and of receivers over eight weeks in their English-speaking class. It employed motivation questionnaires and students’ personal letters to collect their perceptions of each role. The results showed that students generally displayed stronger motivation at the giver role than at the receiver role. In particular, their motivation scores of the communicativeness dimension were significantly different between the two roles because this dimension could easily stimulate their sense of fulfilment and critical thinking when giving feedback. By comparison, for the dimensions of peer accountability and class enjoyment, the students reported similarly modest levels of motivation at both roles because they deemed peer accountability and class enjoyment as sources of extrinsic stimulation and less sustainable than the communicativeness dimension.

Pericytes augment glioblastoma cell resistance to temozolomide through CCL5-CCR5 paracrine signaling

Glioblastoma (GBM) is a prevalent and highly lethal form of glioma, with rapid tumor progression and frequent recurrence. Excessive outgrowth of pericytes in GBM governs the ecology of the perivascular niche, but their function in mediating chemoresistance has not been fully explored. Herein, we uncovered that pericytes potentiate DNA damage repair (DDR) in GBM cells residing in the perivascular niche, which induces temozolomide (TMZ) chemoresistance. We found that increased pericyte proportion correlates with accelerated tumor recurrence and worse prognosis. Genetic depletion of pericytes in GBM xenografts enhances TMZ-induced cytotoxicity and prolongs survival of tumor-bearing mice. Mechanistically, C-C motif chemokine ligand 5 (CCL5) secreted by pericytes activates C-C motif chemokine receptor 5 (CCR5) on GBM cells to enable DNA-dependent protein kinase catalytic subunit (DNA-PKcs)-mediated DDR upon TMZ treatment. Disrupting CCL5-CCR5 paracrine signaling through the brain-penetrable CCR5 antagonist maraviroc (MVC) potently inhibits pericyte-promoted DDR and effectively improves the chemotherapeutic efficacy of TMZ. GBM patient-derived xenografts with high CCL5 expression benefit from combined treatment with TMZ and MVC. Our study reveals the role of pericytes as an extrinsic stimulator potentiating DDR signaling in GBM cells and suggests that targeting CCL5-CCR5 signaling could be an effective therapeutic strategy to improve chemotherapeutic efficacy against GBM.

795 AXIN2+ PERIBILIARY GLAND CELLS IN PERIAMPULLARY REGION SERVE AS BILIARY EPITHELIAL STEM CELLS AND GIVE RISE TO AMPULLARY CARCINOMA

Background and aims Peribiliary glands (PBGs), clusters of epithelial cells residing in the submucosal compartment of extrahepatic bile ducts, have been suggested as biliary epithelial stem/progenitor cell niche; however, evidence to support this claim is limited due to a lack of PBG-specific markers. We therefore sought to identify PBG-specific markers to investigate the potential role of PBGs as stem/progenitor cell niches, as well as an origin of cancer. Methods We examined the expression pattern of the Wnt target gene Axin2 in extrahepatic bile ducts. We then applied lineage tracing to investigate whether Axin2-expressing cells from PBGs contribute to biliary regeneration and carcinogenesis using Axin2-CreERT mice. Results Wnt signaling activation, marked by Axin2, was limited to PBGs located in the periampullary region. Axin2+ cells in periampullary PBGs expressed stem cell markers as well as cell proliferation markers. Lineage tracing revealed that Axin2-expressing periampullary PBG cells are capable of self-renewal and supplying new biliary epithelial cells (BECs) to the luminal surface. Additionally, the expression pattern of Axin2 and CK19 was mutually exclusive in periampullary region, and fate tracing of CK19+ luminal surface BECs revealed gradual replacement by CK19- cells, further supporting the continuous replenishment of new BECs from PBGs to the luminal surface. We also found that R-spondin3 (Rspo3), an enhancer of Wnt signaling, was strongly expressed in the smooth muscle cells adjacent to the lower part of periampullary PBGs. These smooth muscle cells corresponded to human sphincter of Oddi, and similar expression pattern of Axin2 and Rspo3 was observed in human periampullary region. Notably, smooth muscle cell-specific deletion of Rspo3 in mice markedly decreased Axin2 expression in periampullary PBGs and induced significant atrophy of ampulla of Vater. Furthermore, introduction of PTEN deletion into Axin2+ PBG cells (Axin2;PTENΔ/Δ mice), but not CK19+ luminal surface BECs (CK19;PTENΔ/Δ mice), induced ampullary carcinoma. Ampullary carcinoma organoids generated from Axin2;PTENΔ/Δ mice were dependent on Rspo3 for their growth, suggesting that extrinsic stimulation of Wnt signaling is important for the growth of ampullary tumors. In fact, administration of Wnt inhibitor dramatically suppressed ampullary carcinoma development in Axin2;PTENΔ/Δ mice. Conclusion A specific cell population receiving Wnt-activating signal in periampullary PBGs functions as biliary epithelial stem/progenitor cells and also cellular origin of ampullary carcinoma. These new findings can facilitate the development of new therapeutic strategies to induce biliary regeneration, as well as to treat ampullary carcinoma. Download : Download high-res image (147KB) Download : Download full-size image Graphical Abstract

Pupillary unrest, opioid intensity, and the impact of environmental stimulation on respiratory depression

Opioid-induced respiratory depression (OIRD) confers significant morbidity, but its onset can be challenging to recognize. Pain or stimulation effects of conversation may mask or attenuate common clinical manifestations of OIRD. We asked whether pupillary unrest could provide an objective signal of opioid exposure, and whether this signal would be independent from the confounding influence of extrinsic stimulation. We conducted a cross-over trial of healthy volunteers using identical remifentanil infusions separated by a washout period; in both, pupillary unrest in ambient light (PUAL) was measured at 2.5-min intervals. During one infusion, investigators continuously engaged the subject in conversation, while in the other, a quiet environment was maintained; measures of respiratory depression were compared under each condition. We tested PUAL’s relationship to estimated opioid concentration under quiet conditions, measured PUAL’s discrimination of lower versus higher opioid exposure using receiver operating characteristic (ROC) analysis, and assessed the effect of stimulation on PUAL versus opioid using mixed effects regression. Respiratory depression occurred more frequently under quiet conditions (p < 0.0001). Under both conditions, PUAL declined significantly over the course of the remifentanil infusion and rose during recovery (p < 0.0001). PUAL showed excellent discrimination in distinguishing higher versus absent-moderate opioid exposure (AUROC = 0.957 [0.929 to 0.985]), but was unaffected by interactive versus quiet conditions (mean difference, interactive – quiet = − 0.007, 95% CI − 0.016 to 0.002). PUAL is a consistent indicator of opioid effect, and distinguishes higher opioid concentrations independently of the stimulating effects of conversational interaction. Under equivalent opioid exposure, conversational interaction delayed the onset and minimized the severity of OIRD.Clinical trial registration: NCT 04301895

Investigating 'Fear of Missing Out' (FOMO) as an extrinsic motive affecting sport event consumer's behavioral intention and FOMO-driven consumption's influence on intrinsic rewards, extrinsic rewards, and consumer satisfaction.

This study posits that Fear of Missing Out (FOMO) can function as an extrinsic motive stimulating sport event consumption by inducing consumers to overcome leisure constraints. Also, FOMO-driven consumption is proposed to affect consumption experience for being grounded on extrinsic than intrinsic rewards. In Study 1, the moderation of FOMO between intrapersonal and structural constraints and sport media viewing intention are tested. In Study 2, the relations among FOMO-driven consumption, intrinsic rewards (i.e., enjoyment), extrinsic rewards (i.e., social adherence), and consumer satisfaction are assessed. Study 1 results support the notion that FOMO can boost sport media viewing intention through two mechanisms: by directly stimulating intention and by lifting the negative effect of constraints on intention. In Study 2, FOMO-driven consumption shows a stronger link to extrinsic than intrinsic rewards, extrinsic reward is marginally but negatively associated with intrinsic reward, and intrinsic reward is a stronger predictor of satisfaction. Overall, FOMO is identified as a meaningful extrinsic motive for sport event consumption though its effects on consumer satisfaction are arguable. Implications for FOMO-driven marketing are discussed.

Chemical Strategies to Enhance the Therapeutic Efficacy of Toll-like Receptor Agonist Based Cancer Immunotherapy.

Recent developments in the fields of biomedical chemistry and immune bioengineering have enabled innovative therapeutic approaches that can enhance the efficacy, accuracy, and safety of cancer immunotherapy. Among the numerous strategies utilized in cancer immunotherapy, Toll-like receptor (TLR) agonist-based approaches have been studied for a long time since they trigger the innate immune system and generate antigen-specific T cell responses to fight against tumors. In addition to these immunostimulatory functions, TLR agonists also contribute to the reprogramming of immune suppressive tumor microenvironments. Although TLR agonists are now being intensively studied in clinical trials due to their substantial immunomodulatory properties, they still show a low therapeutic index. Nonspecific and random stimulation of various immune cells produces excess levels of proinflammatory cytokines, resulting in cytokine storms and chronic diseases. Therefore, the development of chemical strategies to enhance the therapeutic efficacy as well as the safety of TLR agonist-based immunotherapy is essential and in high demand.In this Account, we summarize and discuss recent developments in biomedical chemistry and bioengineering techniques for the immunomodulation of TLR agonists that have addressed the limitations in current cancer immunotherapy. Immunomodulation of TLR agonists can be classified into two different approaches: (1) molecular modulation via chemical structure modification and (2) macroscopic modulation via an engineered drug delivery system. In molecular modulation, based on prodrug and antedrug principles, activity is modulated (active or inactive) through immolative chemical linkers that can respond to extrinsic or intrinsic biological stimulation and the plasmatic environment, respectively. To increase the effectiveness of TLR agonists as immunostimulatory agents, researchers have conjugated TLR agonists with other immunotherapeutic moieties (antigen, antibody, other TLR agonist, etc.). For macroscopic modulation, bioengineering of delivery carriers differing in size or with albumin hitchhiking moieties has been utilized to increase the efficiency of the targeting of these carriers to secondary lymphoid organs (lymph nodes (LNs) and spleen). The conjugation of specific targeting ligands and incorporation of stimulus-triggering moieties can promote the delivery of TLR agonists into specific cells or intracellular compartments. Implantable porous scaffolds for specific immune cell recruitment and in situ depot-forming gel systems for controlled release of immunomodulatory drugs can increase the therapeutic efficacy of TLR agonists while reducing systemic toxicity. Taken together, these findings show that well-designed and precisely controlled chemical strategies for the immunomodulation of TLR agonists at both the molecular and macroscopic levels are expected to play key roles in improving the therapeutic efficacy of cancer immunotherapy while minimizing immune-related toxicity.

OKUL ÖNCESİ ÖĞRETMEN ADAYLARININ CAN SIKINTISI EĞİLİMLERİ İLE MOBİL TELEFON YOKSUNLUKLARI ARASINDAKİ İLİŞKİ

While it is known that factors such as depression, anxiety, and mood disorders are associated with smartphone addiction, little information is available in the literature about the variables that mediate these relationships. Therefore, in this study, the effect of boredom tendency on mobile phone withdrawal was investigated. In the research, it was aimed to reach the whole study group, which did not go for sampling based on the principle of volunteering. The research is in the pre-school education department in the fall semester of 2019 1.2.3. It was carried out with students who continue their education in the 4th and 4th grades. In the study carried out using the relational research model, the pre- primary school pre-service teachers' boredom tendency and mobile phone deprivation (Nomophobia) were investigated. Two different scales were used to collect the research data. Mobile scale developed by Erden, Turen and Kalkin (2017) to determine students' boredom tendencies with the scale of boredom tendency developed by Vodanovich, Wallece and Kas (2005) and adapted to Turkish. phone deprivation (Nomophobia) scale was used. While analyzing the obtained data, linear regression analysis was made with descriptive analyzes. As a result of the analysis, it was concluded that teacher candidates' boredom tendencies predicted mobile phone deprivation levels. In particular, it was found that the variables of intrinsic stimulation and extrinsic stimulation sub-dimensions of boredom tendencies significantly predicted the factor of not being able to access information and that the extrinsic stimulation factor significantly predicted the factor of not being online from the sub-dimensions of the distress tendency scale. As a result, it has been concluded that the effect of external stimulation on mobile phone deprivation (Nomophobia) is more determinant and directs the individual in the tendency to boredom. Therefore, it can be said that this situation creates anxiety in the individual and leads to more phone usage

Analysis of continuous infusion functional PET (fPET) in the human brain

Functional positron emission tomography (fPET) is a neuroimaging method involving continuous infusion of 18-F-fluorodeoxyglucose (FDG) radiotracer during the course of a PET examination. Compared with the conventional bolus administration of FDG in a static PET scan, which provides an average glucose uptake into the brain over an extended period of up to 30 ​min, fPET offers a significantly higher temporal resolution to study the dynamics of glucose uptake. Several earlier studies have applied fPET to investigate brain FDG uptake and study its relationship with functional magnetic resonance imaging (fMRI). However, due to the unique characteristics of fPET signals, modelling of the fPET signal is a complex task and poses challenges for accurate interpretation of the results from fPET experiments. This study applied independent component analysis (ICA) to analyse resting state fPET data, and to compare the performance of ICA and the general linear model (GLM) for estimation of brain activation in response to tasks. The fPET signal characteristics were compared using GLM and ICA methods to model fPET data from a visual activation experiment. Our aim was to evaluate GLM and ICA methods for analysing task fPET datasets, and to apply ICA methods to the analysis of resting state fPET datasets. Using both simulation and in-vivo experimental datasets, we show that both ICA and GLM methods can successfully identify task related brain activation. We report fPET metabolic resting state brain networks revealed by application of the fPET ICA method to a cohort of 28 healthy subjects. Functional PET provides a unique method to map dynamic changes of glucose uptake in the resting human brain and in response to extrinsic stimulation.

Microenvironmental Alterations in Carbon Nanotube-Induced Lung Inflammation and Fibrosis.

Carbon nanotube (CNT)-induced pulmonary inflammation and fibrosis have been intensively observed and characterized in numerous animal studies in the past decade. Remarkably, CNT-induced fibrotic lesions highly resemble some human fibrotic lung diseases, such as IPF and pneumoconiosis, regarding disease development and pathological features. This notion leads to a serious concern over the health impact of CNTs in exposed human populations, considering the rapidly expanding production of CNT materials for diverse industrial and commercial applications, and meanwhile provides the rationale for exploring CNT-induced pathologic effects in the lung. Accumulating mechanistic understanding of CNT lung pathology at the systemic, cellular, and molecular levels has demonstrated the potential of using CNT-exposed animals as a new disease model for the studies on inflammation, fibrosis, and the interactions between these two disease states. Tissue microenvironment plays critical roles in maintaining homeostasis and physiological functions of organ systems. When aberrant microenvironment forms under intrinsic or extrinsic stimulation, tissue abnormality, organ dysfunction, and pathological outcomes are induced, resulting in disease development. In this article, the cellular and molecular alterations that are induced in tissue microenvironment and implicated in the initiation and progression of inflammation and fibrosis in CNT-exposed lungs, including effector cells, soluble mediators, and functional events exemplified by cell differentiation and extracellular matrix (ECM) modification, are summarized and discussed. This analysis would provide new insights into the mechanistic understanding of lung inflammation and fibrosis induced by CNTs, as well as the development of CNT-exposed animals as a new model for human lung diseases.

Blue Light Promotes Neurite Outgrowth of Retinal Explants in Postnatal ChR2 Mice.

Neurons in the adult mammalian CNS fails to regenerate after severe injury. However, it is known that an increase in neural activity occurs in mouse retinal ganglion cells (RGCs) after extrinsic stimulation and this can induce axon growth. In the present study, we applied an optogenetic approach using a mouse model, specifically involving channelrhodopsin-2 (ChR2) expression in RGCs. We investigated whether modulation of RGC neural activity exclusively by blue light stimulation is able to promote neurite outgrowth of postnatal retinal explants. The results showed that activation of RGCs expressing ChR2 by 20 Hz blue light for 1 h is a most effective way of enhancing neurite outgrowth in postnatal retinas. This is achieved via gap junctions that spread neural activity across the whole retina. Moreover, we found that activation of intrinsic photosensitive RGCs (ipRGCs) by blue light also contributes significantly to the promotion of neurite outgrowth in the same postnatal retinal explants. Our findings not only demonstrate that a short-term increase in RGC neural activity is sufficient to facilitate the neurite outgrowth of retinal explants, but also highlight the fact that the temporal pattern of neural activity in RGCs is a critical factor in regulating axon regeneration.

Role of Renin-Angiotensin-System in Human Breast Cancer Cells: Is There a Difference in Regulation of Angiogenesis between Hormone-Receptor Positive and Negative Breast Cancer Cells?

Objective This study examined the role of the RAS in human breast cancer cells to question if there are differences between HR-positive and HR-negative cells with regard to regulation of VEGF. Methods Expression of different RAS components in hormone receptor (HR)-positive and HR-negative breast cancer cells was investigated using RT-PCR. Different stimulation protocols with different RAS inhibitors were used to investigate the effect on VEGF expression. Angiotensin II-dependent expression of VEGF was quantified by real time PCR. In addition, the effect of intrinsic RAS was studied performing siRNA knockdown of angiotensinogen (AGT). Statistical analysis were calculated using IBM SPSS Statistics Version 21. Results Expression of AT 1 R, AT 2 R, AGT and ACE was shown in HR-positive and HR-negative breast cancer cell lines. Extrinsic stimulation with angiotensin II increased VEGF significantly. After treatment with captopril or AT 1 R-inhibitor candesartan, VEGF-expression decreased significantly in HR-positive and HR-negative cell lines. However, inhibition of AT 2 R using PD 123,319 did not show any significant changes of VEGF. After prevention of intrinsic angiotensin II, extrinsic angiotensin II as well as the combination with inhibitors of the receptors caused a significant reduction of VEGF. Surprisingly, the overall effect of the RAS after knockdown of AGT revealed a significant increase of VEGF in HR-positive cells at any time while a significant decrease was observed in HR-negative cells after 144 hours incubation. Conclusion The RAS-dependent regulation of VEGF between HR-positive and HR-negative breast cancer cells seems do be different. These findings provide evidence for a possible future therapeutic strategy.

Macrophage migration inhibitory factor-CD74 interaction regulates the expression of programmed cell death ligand 1 in melanoma cells.

Expression of programmed cell death ligand 1 (PD‐L1) on tumor cells contributes to cancer immune evasion by interacting with programmed cell death 1 on immune cells. γ‐Interferon (IFN‐γ) has been reported as a key extrinsic stimulator of PD‐L1 expression, yet its mechanism of expression is poorly understood. This study analyzed the role of CD74 and its ligand macrophage migration inhibitory factor (MIF) on PD‐L1 expression, by immunohistochemical analysis of melanoma tissue samples and in vitro analyses of melanoma cell lines treated with IFN‐γ and inhibitors of the MIF‐CD74 interaction. Immunohistochemical analyses of 97 melanoma tissue samples showed significant correlations between CD74 and the expression status of PD‐L1 (P < .01). In vitro analysis of 2 melanoma cell lines, which are known to secrete MIF constitutively and express cell surface CD74 following IFN‐γ stimulation, showed upregulation of PD‐L1 levels by IFN‐γ stimulation. This was suppressed by further treatment with the MIF‐CD74 interaction inhibitor, 4‐iodo‐6‐phenylpyrimidine. In the analysis of melanoma cell line WM1361A, which constitutively expresses PD‐L1, CD74, and MIF in its non‐treated state, treatment with 4‐iodo‐6‐phenylpyrimidine and transfection of siRNAs targeting MIF and CD74 significantly suppressed the expression of PD‐L1. Together, the results indicated that MIF‐CD74 interaction directly regulated the expression of PD‐L1 and helps tumor cells escape from antitumorigenic immune responses. In conclusion, the MIF‐CD74 interaction could be a therapeutic target in the treatment of melanoma patients.

The Zebrafish Heart: an Archetype for Neurocardiology

The intracardiac nervous system (ICNS) is the final common pathway for reflex control of cardiac output by the autonomic nervous system (ANS). The normal operation of this system is key to supporting cardiovascular homeostasis, and ANS dysfunction or remodelling can contribute to the development of multiple cardiopathies. Thus the role of the ICNS in cardiac control is essential, however our current understanding of this role is incomplete. The majority of work on the ICNS to date has been in mammalian models, but because the neural elements comprising this network are embedded in cardiac tissues, visualization and experimental access to the entire network for integrative studies of neuronal function has been limiting. To address these issues, we have developed the zebrafish, a cyprinid teleost, as an alternate model for cardiac anatomical and neurophysiological studies. In this ancestral vertebrate the two‐chambered heart, although anatomically distinct from the mammalian four chamber arrangement, is dually innervated by sympathetic and parasympathetic limbs of the ANS and has a well‐developed ICNS which is functional in spontaneously beating isolated preparations. Activation of extrinsic cardiac nerves evokes tachycardia (via B2‐adrenoceptors) and bradycardia (M2 muscarinic receptors). Thus the essential features of ANS control of the heart are conserved across the vertebrates. We have mapped the general innervation patterns of the sinoatrial valve region (SAR), atrium and ventricle. A ganglionated plexus in the SAR surrounds the valve and contains most of the intracardiac neuronal somata; the majority is cholinergic with the remainder adrenergic, nitrergic and serotonergic. Furthermore, peptidergic axon terminals contact plexal somata. Optical mapping of the isolated heart confirms the site of origin of normal primary pacemaker activity within the SAR, where cells in the base of the valve leaflets express Islet‐1 (Isl‐1) and hyperpolarization‐activated, cyclic nucleotide‐gated channel 4 (HCN4), known markers for mammalian pacemaker cells. In addition, intracellular recordings from these cells display spontaneous diastolic membrane depolarization patterns typical of pacemaker cells. Extrinsic cardiac nerve stimulation, in addition to evoking bradycardia, can displace the pacemaker site to a secondary pacemaker in the atrioventricular region (AVR), where a population of cells also expresses Isl‐1 and HCN4. A small ganglion containing cholinergic somata is present in the AVR, suggesting local neural control of atrioventricular pacemaker activity. We have thus established the zebrafish heart as a viable model for studies of integrative neural control of pacemaker function. In particular, this model provides a platform to use optogenetic techniques to target intracardiac neurons and pacemaker cells, in combination with traditional electrophysiological methods, to perform detailed analyses of the intracardiac neuronal circuitry involved in cardiac control. This work will provide a solid foundation for further studies of ANS‐related cardiac pathophysiologies in zebrafish analogs of human cardiac disease states.Support or Funding InformationNatural Sciences and Engineering Research Council of Canada (FMS, TAQ, RPC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Intrinsic network reactivity differentiates levels of consciousness in comatose patients

ObjectiveWe devise a data-driven framework to assess the level of consciousness in etiologically heterogeneous comatose patients using intrinsic dynamical changes of resting-state Electroencephalogram (EEG) signals. MethodsEEG signals were collected from 54 comatose patients (GCS ⩽ 8) and 20 control patients (GCS > 8). We analyzed the EEG signals using a new technique, termed Intrinsic Network Reactivity Index (INRI), that aims to assess the overall lability of brain dynamics without the use of extrinsic stimulation. The proposed technique uses three sigma EEG events as a trigger for ensuing changes to the directional derivative of signals across the EEG montage. ResultsThe INRI had a positive relationship with GCS and was significantly different between various levels of consciousness. In comparison, classical band-limited power analysis did not show any specific patterns correlated to GCS. ConclusionsThese findings suggest that reaching low variance EEG activation patterns becomes progressively harder as the level of consciousness of patients deteriorate, and provide a quantitative index based on passive measurements that characterize this change. SignificanceOur results emphasize the role of intrinsic brain dynamics in assessing the level of consciousness in coma patients and the possibility of employing simple electrophysiological measures to recognize the severity of disorders of consciousness (DOC).